Pipe insulator and method for making same

Abstract

An electrically insulated pipe coupling and method is disclosed in which a first sleeve member and a second sleeve member are positioned in axial alignment and include oppositely positioned end portions axially spaced from one another to create an axial space therebetween. A resilient annular seal portion is gradually formed in situ (preferably by applying liquid urethane onto a rotating mandrel) in the axial space. The seal portion is chemically bonding to the oppositely positioned end portions and creates a low pressure coupling seal between said first and second sleeve members. An outer protective layer made from continuous synthetic resin saturated fiberglass strand windings is encircled around at least a portion of the end portions of the first and second sleeve members to enclose the seal portion. Finally, a rigid reinforcing sleeve is embedded in and covered by the fiberglass windings of the outer protective layer.

The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. An electrically insulated pipe coupling comprising: a first sleeve member and a second sleeve member positioned in axial alignment and including oppositely positioned end portions axially spaced from one another to create an axial space therebetween;   a resilient annular seal portion gradually formed in situ in said axial space, said seal portion chemically bonding to said oppositely positioned end portions whereby said seal portion provides a low pressure coupling seal between said first and second sleeve members;   an outer protective layer comprising of continuous uncut synthetic resin saturated fiberglass strand windings encircling at least a portion of the end portions of said first and second sleeve members and encircling all of said annular seal portion; and   a rigid reinforcing sleeve embedded in and covered by said fiberglass windings of said outer protective layer.   
     
     
       2. An electrically insulated pipe coupling according to claim 1 wherein said end portions each have a plurality of concentric grooves provided therein. 
     
     
       3. An electrically insulated pipe coupling according to claim 2 wherein at least some of said fiberglass windings are provided in said concentric grooves. 
     
     
       4. An electrically insulated pipe coupling according to claim 1 wherein annular seal has an outer diameter dimension substantially equal to an outer diameter dimension of said first and second sleeve members and said annular seal has an inner diameter dimension substantially equal to an inner diameter dimension of said first and second sleeve members. 
     
     
       5. An electrically insulated pipe coupling according to claim 1 wherein an annular seal portion is gradually formed in situ in a continuously applied layer of a liquid urethane material which hardens into a resilient solid urethane seal. 
     
     
       6. An electrically insulated pipe coupling according to claim 1 wherein said fiberglass windings of said protective outer layer are tension windings which exert a radially inwardly compressive force on said annular seal portion. 
     
     
       7. An electrically insulated pipe coupling comprising: a first sleeve member and a second sleeve member positioned in axial alignment and including oppositely positioned end portions axially spaced from one another to create an axial space therebetween;   a resilient annular seal portion gradually formed in situ in said axial space, aid seal portion chemically bonding to said oppositely positioned end portions whereby said seal portion provides a low pressure coupling seal between said first and second sleeve members;   an outer protective layer comprising of continuous synthetic resin saturated fiberglass strand windings encircling at least a portion of the end portions of said first and second sleeve members and encircling all of said annular seal portion, said outer protective layer including radially innermost windings which are provided in a closely spaced hoop winding pattern; and   a rigid reinforcing sleeve embedded in and covered by said fiberglass windings of said outer protective layer.   
     
     
       8. An electrically insulated pipe coupling comprising: a first sleeve member and a second sleeve member positioned in axial alignment and including oppositely positioned end portions axially spaced from one another to create an axial space therebetween;   a resilient annular seal portion gradually formed in situ in said axial space, said seal portion chemically bonding to said oppositely positioned end portions whereby said seal portion provides a low pressure coupling seal between said first and second sleeve members;   an outer protective layer comprising of continuous synthetic resin saturated fiberglass strand windings encircling at least a portion of the end portions of said first and second sleeve members and encircling all of said annular seal portion, said outer protective layer including radially outermost windings which are provided in a widely spaced helical winding pattern; and   a rigid reinforcing sleeve embedded in and covered by said fiberglass windings of said outer protective layer.   
     
     
       9. An electrically insulated pipe coupling according to claim 1 wherein said rigid reinforcing sleeve and said first and second sleeve members are formed of metal and said annular seal portion and said outer protective layer is formed of an electrically non-conductive materials. 
     
     
       10. An electrically insulated pipe coupling according to claim 1 wherein terminal end portions of said first and second sleeve portion include a beveled or a curved surface. 
     
     
       11. A method for making an electrically insulated pipe coupling comprising the steps of: positioning and securing a first sleeve member and a second sleeve member in axial alignment onto a mandrel with end portions of said first and second sleeve members axially spaced from one another with an axial space therebetween through which said mandrel fully extends;   rotating said mandrel and said secured sleeve members;   applying a liquid urethane material onto said rotating end portions and onto said mandrel which extends through said axial space to gradually form a resilient seal portion between said end portions thereby joining said end portions together in a sealing engagement;   encircling said end portions and said seal portion with continuous synthetic resin saturated fiberglass strand windings to form an outer protective layer; and   placing a rigid reinforcing sleeve onto said outer protective layer when said layer is partially formed and thereafter completing the formation of said outer protective layer whereby said rigid reinforcing sleeve is embedded in and covered by said fiberglass windings of said outer protective layer.   
     
     
       12. A method according to claim 11 further comprising the step of cutting a plurality of concentric grooves into said ends the first and second sleeve member prior to securing said members onto said mandrel. 
     
     
       13. A method according to claim 12 wherein at least some of said fiberglass windings are provided in said concentric grooves. 
     
     
       14. A method according to claim 11 wherein said liquid urethane is applied until said annular seal portion has an outer diameter dimension substantially equal to an outer diameter dimension of said first and second sleeve members. 
     
     
       15. A method according to claim 11 wherein the portion of said mandrel which extends through said axial space has an outer diameter dimension substantially equal to the inner diameter dimension of said first and second sleeve members. 
     
     
       16. A method according to claim 11 wherein said fiberglass windings of said protective outer layer are encircled around said end portions and said seal portion under high tension to exert a radially inwardly compressive force on said annular seal portion. 
     
     
       17. A method according to claim 11 wherein said fiberglass windings of said protective outer layer are initially encircled around said sleeve ends and said annular seal portion in a closely spaced hoop winding pattern. 
     
     
       18. A method according to claim 11 wherein radially outermost windings of said protective outer layer are encircled around said sleeve ends and said annular seal portion in a widely spaced helical winding pattern. 
     
     
       19. A method according to claim 11 wherein said rigid reinforcing sleeve and said first and second sleeve members are formed of metal and said annular seal portion and said outer protective layer are formed of an electrically non-conductive materials. 
     
     
       20. A method according to claim 11 further comprising the step of beveling or curving terminal end portions of said first and second sleeve members. 
     
     
       21. A method according to claim 11 further comprising the step of applying a chemical primer solution to said end portions prior to applying said liquid urethane.